content: /* Copyright (C) 2016-2018 Alibaba Group Holding Limited
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  ==============================================================================*/
  
  // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf;
  
  import static com.google.protobuf.Internal.checkNotNull;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InvalidObjectException;
  import java.io.ObjectInputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.nio.InvalidMarkException;
  import java.nio.charset.Charset;
  import java.util.Collections;
  import java.util.List;
  
  /**
   * A {@link ByteString} that wraps around a {@link ByteBuffer}.
   */
  final class NioByteString extends ByteString.LeafByteString {
    private final ByteBuffer buffer;
  
    NioByteString(ByteBuffer buffer) {
      checkNotNull(buffer, "buffer");
  
      // Use native byte order for fast fixed32/64 operations.
      this.buffer = buffer.slice().order(ByteOrder.nativeOrder());
    }
  
    // =================================================================
    // Serializable
  
    /**
     * Magic method that lets us override serialization behavior.
     */
    private Object writeReplace() {
      return ByteString.copyFrom(buffer.slice());
    }
  
    /**
     * Magic method that lets us override deserialization behavior.
     */
    private void readObject(@SuppressWarnings("unused") ObjectInputStream in) throws IOException {
      throw new InvalidObjectException("NioByteString instances are not to be serialized directly");
    }
  
    // =================================================================
  
    @Override
    public byte byteAt(int index) {
      try {
        return buffer.get(index);
      } catch (ArrayIndexOutOfBoundsException e) {
        throw e;
      } catch (IndexOutOfBoundsException e) {
        throw new ArrayIndexOutOfBoundsException(e.getMessage());
      }
    }
  
    @Override
    public int size() {
      return buffer.remaining();
    }
  
    @Override
    public ByteString substring(int beginIndex, int endIndex) {
      try {
        ByteBuffer slice = slice(beginIndex, endIndex);
        return new NioByteString(slice);
      } catch (ArrayIndexOutOfBoundsException e) {
        throw e;
      } catch (IndexOutOfBoundsException e) {
        throw new ArrayIndexOutOfBoundsException(e.getMessage());
      }
    }
  
    @Override
    protected void copyToInternal(
        byte[] target, int sourceOffset, int targetOffset, int numberToCopy) {
      ByteBuffer slice = buffer.slice();
      slice.position(sourceOffset);
      slice.get(target, targetOffset, numberToCopy);
    }
  
    @Override
    public void copyTo(ByteBuffer target) {
      target.put(buffer.slice());
    }
  
    @Override
    public void writeTo(OutputStream out) throws IOException {
      out.write(toByteArray());
    }
  
    @Override
    boolean equalsRange(ByteString other, int offset, int length) {
      return substring(0, length).equals(other.substring(offset, offset + length));
    }
  
    @Override
    void writeToInternal(OutputStream out, int sourceOffset, int numberToWrite) throws IOException {
      if (buffer.hasArray()) {
        // Optimized write for array-backed buffers.
        // Note that we're taking the risk that a malicious OutputStream could modify the array.
        int bufferOffset = buffer.arrayOffset() + buffer.position() + sourceOffset;
        out.write(buffer.array(), bufferOffset, numberToWrite);
        return;
      }
  
      ByteBufferWriter.write(slice(sourceOffset, sourceOffset + numberToWrite), out);
    }
  
    @Override
    void writeTo(ByteOutput output) throws IOException {
      output.writeLazy(buffer.slice());
    }
  
    @Override
    public ByteBuffer asReadOnlyByteBuffer() {
      return buffer.asReadOnlyBuffer();
    }
  
    @Override
    public List<ByteBuffer> asReadOnlyByteBufferList() {
      return Collections.singletonList(asReadOnlyByteBuffer());
    }
  
    @Override
    protected String toStringInternal(Charset charset) {
      final byte[] bytes;
      final int offset;
      final int length;
      if (buffer.hasArray()) {
        bytes = buffer.array();
        offset = buffer.arrayOffset() + buffer.position();
        length = buffer.remaining();
      } else {
        // TODO(nathanmittler): Can we optimize this?
        bytes = toByteArray();
        offset = 0;
        length = bytes.length;
      }
      return new String(bytes, offset, length, charset);
    }
  
    @Override
    public boolean isValidUtf8() {
      return Utf8.isValidUtf8(buffer);
    }
  
    @Override
    protected int partialIsValidUtf8(int state, int offset, int length) {
      return Utf8.partialIsValidUtf8(state, buffer, offset, offset + length);
    }
  
    @Override
    public boolean equals(Object other) {
      if (other == this) {
        return true;
      }
      if (!(other instanceof ByteString)) {
        return false;
      }
      ByteString otherString = ((ByteString) other);
      if (size() != otherString.size()) {
        return false;
      }
      if (size() == 0) {
        return true;
      }
      if (other instanceof NioByteString) {
        return buffer.equals(((NioByteString) other).buffer);
      }
      if (other instanceof RopeByteString) {
        return other.equals(this);
      }
      return buffer.equals(otherString.asReadOnlyByteBuffer());
    }
  
    @Override
    protected int partialHash(int h, int offset, int length) {
      for (int i = offset; i < offset + length; i++) {
        h = h * 31 + buffer.get(i);
      }
      return h;
    }
  
    @Override
    public InputStream newInput() {
      return new InputStream() {
        private final ByteBuffer buf = buffer.slice();
  
        @Override
        public void mark(int readlimit) {
          buf.mark();
        }
  
        @Override
        public boolean markSupported() {
          return true;
        }
  
        @Override
        public void reset() throws IOException {
          try {
            buf.reset();
          } catch (InvalidMarkException e) {
            throw new IOException(e);
          }
        }
  
        @Override
        public int available() throws IOException {
          return buf.remaining();
        }
  
        @Override
        public int read() throws IOException {
          if (!buf.hasRemaining()) {
            return -1;
          }
          return buf.get() & 0xFF;
        }
  
        @Override
        public int read(byte[] bytes, int off, int len) throws IOException {
          if (!buf.hasRemaining()) {
            return -1;
          }
  
          len = Math.min(len, buf.remaining());
          buf.get(bytes, off, len);
          return len;
        }
      };
    }
  
    @Override
    public CodedInputStream newCodedInput() {
      return CodedInputStream.newInstance(buffer, true);
    }
  
    /**
     * Creates a slice of a range of this buffer.
     *
     * @param beginIndex the beginning index of the slice (inclusive).
     * @param endIndex the end index of the slice (exclusive).
     * @return the requested slice.
     */
    private ByteBuffer slice(int beginIndex, int endIndex) {
      if (beginIndex < buffer.position() || endIndex > buffer.limit() || beginIndex > endIndex) {
        throw new IllegalArgumentException(
            String.format("Invalid indices [%d, %d]", beginIndex, endIndex));
      }
  
      ByteBuffer slice = buffer.slice();
      slice.position(beginIndex - buffer.position());
      slice.limit(endIndex - buffer.position());
      return slice;
    }
  }
  